1. Technical Field
The present invention relates to light-emitting devices, such as organic electroluminescence (EL) panels, methods for driving such light-emitting devices, and electronic apparatuses equipped with such light-emitting devices.
2. Related Art
It is generally known that organic EL materials used for light-emitting elements in organic EL panels, which are an example of light-emitting devices, are problematic in that the brightness varies depending on the ambient temperature due to the unique temperature characteristics of the materials. Especially in RGB-independent-emission panels, the differences in the unique temperature characteristics of the materials can induce a color shift, which significantly lowers the display quality. The term “color shift” refers to a change (shift) in the current-versus-light output characteristic caused by temperature differences occurring within a substrate plane (that is, among pixels in the central region and pixels in the periphery regions), a change (shift) in the current-versus-light output characteristic caused by different temperature characteristics among R, G, and B, or a change (shift) in the current-versus-light output characteristic caused by heat generated by TFTs or peripheral circuits (wiring). JP-A-2001-3565D discloses an example of a technique for solving this problem, in which measurement EL elements are provided as temperature sensors for measuring the temperature of the organic EL panel. In this technique, a drive waveform to be applied to the organic EL elements is corrected on the basis of the measured temperature.
With the technique disclosed in JP-A-2001-35655, however, the temperature sensors are disposed in areas other than the display area of the substrate on which the light-emitting elements are disposed. This is technically problematic in that it is difficult to measure the temperature of the light-emitting elements with high accuracy. Supposedly, if the temperature sensors are to be disposed within the display area of the substrate, the substrate may unfavorably need to be given a complicated structure, such as a multilayer structure, or the aperture ratio of the display area may undesirably become reduced. In particular, providing a temperature sensor in the central region of the substrate is not only difficult in terms of circuit wiring, but can also cause heat generation and heat radiation by the wiring lines. On the other hand, setting the sensors externally to the luminescence panel will not make the most of the advantages of organic EL panels, such as compact, low-profile, and lightweight features.